C
Which graph shows the solution to the system of linear inequalities?
2 answers:
Answer:
None of them
Step-by-step explanation:
Both inequalities are shown with < (less than) symbols. Thus the boundary line on both plots of the solution graph should be dashed (not solid) lines. The best choice is the last graph (attached), but the marked line should be dashed, not solid.
The first inequality can be rewritten as ...
... y > (1/4)x -1
The y-intercept of the boundary line will be -1, and the slope of it will be 1/4. Since the inequality symbol is > (not ≥), the boundary line should be dashed. The acceptable values of y are greater than those on the line, so the (blue) shading will be above the line.
The second inequality has a boundary line with a slope of 1 and a y-intercept of +1. Since the inequality symbol is < (not ≤), the boundary line should be dashed (as it is in the attached graph). Acceptable values of y are less than those on the line, so the (red) shading will be below the line.
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Answer:
a) We need a sample size of at least 3109.
b) We need a sample size of at least 4145.
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of , and a confidence level of
, we have the following confidence interval of proportions.
In which
z is the zscore that has a pvalue of .
The margin of error is:
99% confidence level
So , z is the value of Z that has a pvalue of
, so
.
(a) he uses a previous estimate of 25%?
we need a sample of size at least n.
n is found when . So
We need a sample size of at least 3109.
(b) he does not use any prior estimates?
When we do not use any prior estimate, we use
So
Rounding up
We need a sample size of at least 4145.